There are many situations in which it is desirable for a viewing system to be remotely located from a point of observation. For example, a person may desire to remain in a hidden or protected environment, but with the use of viewing apparatus be able to observe distant objects. Periscopes comprise such apparatus and are highly advantageous when used in connection with marine vessels or ground vehicles. Submarines and armored tanks, for example, employ such apparatus which are beneficial to military personnel.
A rudimentary periscope includes upper and lower canted reflective mirrors for redirecting an image in a horizontal displaced or offset manner. A person can thus look into the bottom mirror and observe the object image reflected thereon by the top mirror. The image as observed by both eyes of the person is identical, as it is reflected from a single planar surface.
More sophisticated optical viewing systems which route the image in an offset horizontal manner include provisions for the optical correction of the image as individually presented to each eye of the person. This individual optical or diopter correction requires the image to be split and redirected in separate optical paths toward the respective eyes of the person. Separate eyepieces are provided to accomplish such optical correction. Separate eyepieces not only allow for individual optical adjustment of each eyepiece, but also allow for interpupilary or physical positioning with regard to the eye spacing of various individuals. Separate eyepieces also prevent ambient light from affecting the presentation of the image to the observer.
U.S. Pat. No. 4,463,252 discloses one approach conventionally employed in splitting the image of an observed object The technique employed in the noted patent is to place a reflective member with two angled reflective surfaces within the optical path. In this manner, a portion of the image is reflected in a single plane from one surface in one direction while the remaining portion of the image is reflected from the other surface in another direction. Typically, a right angled reflective member with polished or mirrored surfaces is placed in the optical path to split the image into oppositely directed directions. The routing of the image through the planar optical path is of little aid in periscope-type equipment where the image must traverse a three dimensional optical path.
It can be seen from the foregoing that a need has arisen for an image splitter which can redirect an image through a three dimensional optical path.